Electrical apparatus



Feb. 20, 1923. 1,445,929.

W. R. G. BAKER.

ELECTRICAL APPARATUS.

FILED OCT. 7, 1920.

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25 connected between the anode and cathode- Patented Feb. a, was.

MATES WALTER R. G. BAKER, OF SCHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELEC- TRIO COMPANY, A CORPORATION OF NEW YORK. v

ELECTRICAL APPARATUS.

Application filed October 7, 1920. Serial No. 415,263.

To all whom/it may concern."

- Be it known that L-WALTER R. G..BAKER,

a citizen of the United States, residing at Schenectady, in the county of Schenectady, State of New York, have invented certain new and useful Improvements in Electrical Apparatus, of which the following is a speci-.

fication.

This invention relates to the production of electric waves and more particularly to methods and apparatus for producing a succession of waves which may be modified in accordance with impulses produced, for example,at a controlling'or signalling station.

Apparatus of this character usually consists of a source of electric power, means for converting the energy of said source into current of an oscillatory character and a transmitter for suitably modifying the characterof the oscillations. An amplifier for the initial signalling impulses is often used and this as well as the oscillator may consist of a vacuum discharge device which comprises anjanode, cathode anddischarge controlling grid. A suitable source of current is and the current from this source is modified by changing the potential of the grid in accordance with the impulses which itis'desired to transmit. It is proposed to provide a single source of current for the oscillator and amplifier. When, however, an attempt is made to change the potential of this source to change the output of the oscillator, as for example when it is desired to increase the distance over which messages are to be sent, it-is found that amplifier which is likewise influenced by the changed potential will not operate as effectively unless a corresponding change is made in the normal potential applied to the grid. My present invention provides for the simultaneous changing of the potential of the'common source above referred to and of thepotential applied to the am lifier grid.

ther objects and advantages will appear B is a modulator or amplifier tube having aplate 13, grid 14 and filamentary cathode 15, and C is a dynamo electric generator having an armature 16 and shunt field winding 17.

Plate 10 of the oscillator A is connected to the positive terminal of the generator through coil 18 of the antenna transformer. Likewise interposed in this connection are the inductive resistance'19 and condenser 20 arranged in parallel as shown. Filament 12 mane;

is connected to the negative terminal of the I generator C and to the rid 11 through condenser 21 and coil '22. he,customary leakage resistance bridges the condenser 21.

.Coil 23 of the antenna transformer is in inductive relation both to the coil 22 inthe grid circuit and to coil 18 in the plate circuit of the oscillator A.

The fila-mentary cathode 15 of the modulator B is connected to the negative terminal of the generator C and the plate 13 is connected to the positive terminal of said generator through a reactance-2,4 and the condenser and reactance 20 and 19. Reactance 24 prevents the vacuum tube B from shortcircuiting the radio frequency current. Connected in a circuit from the filament. 15 to the grid 14 is the secondary of the transformer 25 whose primary is in circuit with the local battery 26 and telephone transmitter 27.-

The circuit between the grid 14 and filament 15 includes the switch arm 28 which is secured to the shaft 29, Rotation of the that the difference of potential between thev filament 15 and the grid 14 is varied. Shaft 29 likewise carries an arm 31 which is included in the shunt field circuit of the generator C and by its movement operates to change the amount of the resistance 32 included in the saidfield circuit. Due to the coupling of the coils 18 and 22 with the coil 23 of the antenna circuit and its connection withvthe generator C the oscillator -A is capable of producing high fraquency currents in the antenna transformer. Condenser 20 is of such capacity as will enable the high frequencycurrents in the plate circuit to pass around the inductance 19. The current which is supplied to the amplifier B from the source C is caused to vary in accordance with the sounds in the transmitter 27 by the change in the potential of the grid 14 due to the currents induced in the secondary of the transformer 25. The current in the' plate circuit of the amplifier variation of this current gives B passes through the inductance 19 and the rise to a difference of potential in the inductance 19 which difierence of potential is applied to the plate circuit of the oscillator. This causes the oscillations of the antenna circuit to be correspondingly modified. When it is desired to increase the power of the antenna circuit, shaft 29 is rotated to remove a section of the resistance 32 from the shunt field circuit of the generator 0. This increases the potential of the generator. Simultaneously with the removal of the resistance from the shunt field circuit, a section of the battery 30 is added to the circuit from the filament 15 to potential of the grid 14 by an amount sufii cient to enable the amplifier to continue its effective operation.-

While I have shown an oscillator of the vacuum tube type, it is obvious that some other type of oscillator may be employed.

It is likewise apparent that other means may be employed for controlling the potential of the source C and also for controlling the potential applied to the grid 14.

What I claim as new and desire to secure by Letters Patentof the United States, is

1. In an electrical system, an oscillator, a modulator of the vacuum tube type having plate and grid circuits, a source of current for the plate circuit and for the oscillator, a source of potential for the grid circuit and a single means for simultaneously varying the normal potentials applied to said plate circuit and oscillator and to said grid circuit.

the grid 14. This alters the 2. A method of regulating the output of a transmitting system which includes an oscillator, vacuum tube modulator having a plate circuit and a discharge controlling grid and a source of current supplying said oscillator and the plate circuit of said modulator which consists in simultaneously varying the normal potential of said source and the potential applied to the grid of said modulator. I

3. A combination with an oscillator having coupled grid and plate circuits and a modulator having grid and plate circuits, of a common source of current for said plate circuits, a source of potential for the grid circuit of said modulator and a single means for simultaneously varying the potential of said sources.

4. A combination with an antenna circuit of the oscillator having plate and grid circuits in inductive relation to said antenna circuit, a transmitter circuit, a modulator having a plate circuit and a grid circuit in inductive relation to said transmitter circuit, a source of potential comprising a shunt wound dynamo electric machine connected to said'plate circuits, a resistance in the shunt field circuit of said dynamo electric machine, a battery, and a single means for simultaneously inserting sections of said battery into the grid circuit of said modulator and removing sections of said resistance from the shunt field circuit of said generator.

In witness whereof, I have hereunto set my hand this 6th day of October. 1920.

WALTER R. G. BAKER. 

